Photoluminescence properties of the high-brightness Eu(3+)-doped KNaCa2(PO4)2 phosphors.

A series of red-emitting phosphors Eu(3+)-doped KNaCa2(PO4)2 were synthesized by solid-state reaction, and the photoluminescence (PL) properties were also investigated. The excitation spectrum is composed of charge-transfer (CT) of Eu-O and excitation lines of Eu(3+) ions. The strongest excitation lines appeared at 393 nm. The emission spectra of KNaCa2(PO4)2:Eu(3+) phosphors exhibit five peaks assigned to the (5)D0-(7)FJ (J=0, 1, 2, 3, 4) transitions of Eu(3+) and have dominating emission peak at 621 nm under 393 nm excitation. The luminescence intensity enhanced with increasing Eu(3+) content and the emission reached the maximum intensity at x=0.02 in KNaCa2-x(PO4)2:xEu(3+). The effect of the charge compensators on the emission intensity of the phosphors was investigated. The integral intensity of the emission spectrum of KNaCa1.96(PO4)2:0.02Eu(3+), 0.02Na(+) excited at 393 nm is about 2.4 times as strong as that of Y2O3:0.05Eu(3+) commercial red phosphor. The color coordinates for KNaCa1.96(PO4)2:0.02Eu(3+),0.02Na(+) were measured. The results indicate that KNaCa2(PO4)2:Eu(3+) might be a promising phosphor for w-LEDs.